The inventive concept relates generally to electronic memory technologies. More particularly, certain embodiments of the inventive concept relate to memory systems and related methods of operation in which memory cells are erased by a multi-step process based on stored metadata.
Memory devices may be roughly divided into two categories according to whether they retain stored data when disconnected from power. These categories include volatile memory devices, which lose stored data when disconnected from power, and nonvolatile memory devices, which retain stored data when disconnected from power. Examples of volatile memory devices include static random access memory (SRAM) devices, dynamic random access memory (DRAM) devices, and synchronous DRAM (SDRAM) devices. Examples of nonvolatile memory devices include flash memory devices, read only memory (ROM) devices, programmable ROM (PROM) devices, electrically erasable and programmable ROM (EEPROM) devices, and various forms of resistive memory such as phase-change RAM (PRAM), ferroelectric RAM (FRAM), and resistive RAM (RRAM).
In certain types of flash memory devices, such as vertical NAND (VNAND) flash memory devices using charge trapped flash (CTF) cells, erase operations may take a relatively long time and can therefore affect overall system performance. Consequently, there is a general need to improve systems to cope with or reduce this relatively long erase time.